When I was in Dublin I stayed here - http://www.avondale.ie Didn't have a en-suite but I turned up without anywhere to stay and was on my todd so wasn't too picky about what room I got. At least I think it was that one, it might have been http://www.budgetplaces.com/dublin-hostel-18313-the-holyhead-hostel.html but I know it was across the street from http://www.osheashotel.com/